I purposely removed the specific cases, to talk about the more general concept of "law". Humans will have great difficulty having a reasonable debate over a specific law like in the examples you have chosen. (They are particularly emotive ones)

I don't believe I can conclude on my own whether society benefits from the existence of laws, nor can I say that any one law benefits society.

I believe that I can conclude on my own that a law making homosexuality punishable by death does not >benefit society.

These statements are not mutually exclusive. I'd like to try again to be clear that I meant "The existence of laws" not "the existence of this one specific law".

I believe that I can conclude on my own that a law making homosexuality punishable by death does not benefit society.

In the interest of demonstrating (my point) the inability to reason one law's benefits to society (or to prove your point) - please reason out your entire conclusion from start to finish of why:

a law making homosexuality punishable by death does not benefit society.

I expect this reasoning to be some thousands of words long to reason out entirely your point. (because precisely my point is that its not that simple)

For your second comment; Can you make the argument without referring to a specific law?

(also please refrain from making judgements on others, feel free to judge an argument, tear it to shreds; but not the person who makes it)

Apologies for the edit: I seem to be having troubles getting formatting to work the way I want it to.